1. Field of the Invention
This invention details a process for control and clean up of minor and massive oil spills from the surface of water using pre-treated peanut hulls as sorbent. Method for producing such sorbent and its appropriated application technique in open waters are also detailed.
2. Introduction
It is well known that oil spills in open waters produce serious ecological, environmental and economical damage. According to the National Research Council estimates, the sources and amounts of oil-related pollutants dumped into the oceans each year are:
Down the Drain: 363 million gallons, including used engine oil that constitutes run-off from land, and municipal and industrial waste.
Routine Maintenance: 137 million gallons including bilge cleaning and other ship releases.
Up in smoke: 92 million gallons including air pollution, mainly from cars and industry.
Natural Seeps: 62 million gallons including seepage from ocean bottom and eroding sedimentary rocks.
Big Spills: 37 million gallons including tanker accidents.
Large spills, even though a relatively minor source of ocean oil pollution, can be devastating. Only about five percent of oil pollution in oceans are due to major tanker accidents, but one big spill can disrupt sea and shore life for miles. The impact of oil on shorelines may be particularly great where large areas of rocks, sand and mud are uncovered at low tide. The National Oceanic and Atmospheric Administration estimates that the Exxon Valdez accident of 1989 in Alaska spilled around 11 million gallons of crude oil, killing 350,000 to 390,000 water fowl, 3,500 to 5,500 sea otters, and cost more than five billion US dollars. The impact on marine life was compounded by toxicity and tainting effect resulting from the chemical composition of the oil, as well as by the diversity and variability of biological systems and their sensitively to oil pollution. According to the same source of information, three years later the relative percent distribution of the oil mass released into the environment was:
50% Biodegraded/Photolysed
20% Atmospheric photolysis
14% Recovered
13% Subtidal sediment
2% Beached
1% Dispersed in water
From the above results it is clear that even after catastrophic spills like the Valdez, with enough time natural forces act to counteract the pollution. However, the worst immediate consequences of a massive oil spill are due to the shock produced by the overwhelming mass of hazardous substances suddenly released into an environment which was not prepared to digest it and unable to restore itself to its original condition by itself in a short time.
Thus, we can deduct that one of the fundamental aims of oil spill response strategies should be to react as soon as possible with appropriate countermeasures in order to restrict or minimize the spread of the damage. With that purpose in mind, it is the aim of the present invention to propose an alternative response methodology conceived for the treatment and remedy of extended polluted water surfaces with celerity, bearing in mind that the areal distribution of the injury is time dependent.
It is important to emphasize here that a sorbent composition of the present invention is apt and can be used with the same comparative advantages in many different situations, such as for treatment and remedy of routine maintenance spills, land spills and others, and may be applied directly on the polluted surface by any classical methodology. The preferred embodiment mainly focuses on an oil spill in open waters because, as it is well known to the skilled in the art, it is probably the worst condition to control, handle and remedy. The clean-up components are exposed to the punishing mercy of the elements, and are under dynamic conditions.
Many compounds, apparatus and techniques were proposed by the prior art to facilitate the mitigation of deleterious effect or the removal of oil pollutants from water. In a general sense, the scope of available tools and methodologies to combat such pollution can be summarized as follows:
Chemical Agents: elements, compounds or mixtures that coagulate, disperse, dissolve, emulsify, foam, neutralize, precipitate, reduce, solubilize, oxidize, concentrate, congeal, entrap, fix, make the pollutant mass more rigid or viscous. The above compounds include biological additives, dispersants, sinking agents, burning agents, but do not include solvents. Chemical Agents have been applied to disperse and biodegrade oil spills; however, such applications, far from be beneficial, could result in worse environmental damage.
Apparatus: skimmers, booms, pumps, hydrocyclones, barriers, mechanical separators, containers, filters, bags, separators, recovery vessels, etc. Apparatus are of limited effectiveness for the control and recovery of extended oil spills, and are very difficult or are unfeasible to be used under adverse meteorological conditions.
Sorbents: essentially inert and insoluble materials that are used to remove oil and hazardous substances from water through adsorption and/or absorption. They include:
a) organic products (peat, moss or straw, cellulose fibers or cork, corn cobs, chicken or duck feathers, wood chips, cereals;
b) mineral compounds, volcanic ash or perlite, vermiculite or zeolite;
c) synthetic products (polypropylene, polyethylene, polyurethane, polyester).
Mineral sorbents are of relatively high density, and after their spread on top of the water surface they sink to the bottom forming a stationary layer saturated with oil that affects the benthos. Synthetic sorbents are not biodegradable per se and need to be recovered and processed by treatment facilities for disposal Organic sorbents, including the herein proposed option, are biodegradable, non toxic, effective and usually cheap.
There are known the following patents related to the application based on methods of utilization of natural organic sorbents:
U.S. Pat. No. 3,617,564 disclosing the utilization of corncob components for the removal of oil spills from water and land.
U.S. Pat. No. 3,902,998 disclosing a method for removing oil from water based on the utilization of rice hulls as sorbent.
U.S. Pat. No. 4,959,154 disclosing the utilization of pre-treated wood chips for the cleanup of water and land oil spills.
U.S. Pat. No. 4,969,774 disclosing the use of pre-cooked and puffed cereals as oil spill sorbents.
U.S. Pat. No. 5,114,593 disclosing the application of dry and pulverized aquatic lily plant to the spilled oil.
U.S. Pat. No. 5,160,629 disclosing a method for removing organic substances from bodies of water using entire dried corn cobs in their natural state.
U.S. Pat. No. 5,352,780 discloses a method for absorbing, removing and cleaning up a liquid floating in a second liquid, employing absorbent pellets made from cellulose flakes.
Peanut shells were previously used as particulate cellulosic raw material for the production of a carbonaceous residue product or char. U.S. Pat. No. 4,145,256 discloses the procedure and apparatus for the carry out of such an operation. Even though at first glance some similitude exists to the above patent with the proposed sorbent pre-treatment methodology herein, the basic fabrication principles and resulting final products are clearly different. These differences will be evident after a detailed examination and comparison between both technical procedures, and can be summarized as follows:
in the abovementioned U.S. Pat. No. 4,145,256, peanut shells are submitted to a destructive discomposure. Reaction temperatures vary between 526xc2x0 C. (975xc2x0 F.) to 1315xc2x0 C. (2410xc2x0 F.); the result is that the final product is a devolatilized powdered or carbonaceous residue or char, having an elemental carbon content in excess of about ninety percent by weight.
in the same US patent such high temperatures are reached by the use of a controlled amount of forced air introduced into the system that produces the exothermic oxidation of the heavy tars distilled from shells.
in the same process, the heavier distilled tars condense on the shells in the upper strata of the reaction chamber; they migrate to the maximum temperature region of that chamber whereby they progressively further discompose and carbonize to build up the final carbonaceous residue product.
It is the aim of the present invention to provide a sorbent composition and apparatus to combat oil spills and other hazardous pollutants floating on or in water, based on the utilization of pre-treated peanut hulls as sorbent and complemented by a specific application technique of such sorbent for the cleanup of such oil spills in open waters.
The selection criteria for the utilization of peanut hulls as sorbent was found in the following characteristics and advantages:
peanut hulls, as a natural vegetal product, are non toxic, biodegradable and innocuous in any amount applied;
as waste or byproduct of the peanut industry, the sorbent is cheap, abundant, and their pre-treatment is simple and economical;
to be complementary to the proposed application technique in open waters, the sorbent needs to be the least dense possible; adequately pre-treated, it needs to maintain its oleophilic characteristics even after it has been immersed in water for a considerable time before contact with the oiled surface;
under the herein proposed dosage ratio, the sorbent acts immediately and retains the sorbed oil with enough tenacity to minimize the tainting effect by the occasional physical contact of the oiled mass with any solid dry or wet surface (animal, rocks, beach, etc); it also works satisfactorily with crude oils of different viscosity and density;
after the application and impregnation, the oiled sorbent forms a buoyant rimed-like layer that permits its control and collection by mechanical devices (booms, skimmers, pumps, nets, etc.) during a reasonable time, and can be subsequently introduced into a recovery process if desired;
some hours after its application, the oiled sorbent acts as particulate physical dispersant, with the advantage that the oiled mass does not need be necessarily recovered to mitigate the damage;
after the oil/water saturation, the sorbent tends to reach an equilibrium condition with a final apparent maximum density of about 1.27 g/cm3, and behaves in that medium like any other light vegetal detritus, preventing the subsurface penetration of oil into cobble and boulder beaches. The washed-up material on shore is dry to the touch after its natural water evaporation and drying, does not stain, and can be easily recovered by vacuum techniques;
with the abovementioned physical sorbent characteristics, the application technique in open waters can be conceived to sweep extended polluted water surfaces efficiently, in a short time, can be used under adverse meteorological conditions, and is apt for the cleanup of partially ice-covered water surfaces.
According to the National Agricultural Statistics Service, USDA, the production of peanuts in the US during 1998 was about 1,800,000 tons. Roughly three-quarters of the peanuts grown are used domestically as edible products. About one-fourth of the production is exported to other countries. From the approximately 1,300,000 tons consumed yearly in the US, 10% is sold as in-shell peanuts (Valencia variety). The remaining 90% (Runner variety), about 1,170,000 tons, are commercialized shelled.
Considering that in one pod (Runner variety), the shell represents roughly 18% of the total weight, the result is that about 200,000 tons of waste or by-product shells are theoretically available each year for diverse uses. At the present time, shells are mostly actually used in wallboard, fire place logs, fiber roughage for livestock and kitty litter.